Pulse radiolysis studies of intermolecular charge transfers involving tryptophan and three-electron-bonded intermediates derived from methionine

Fu, H. Y.*; Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*

In the present work, pulse radiolysis was used to demonstrate the oxidizing nature of various intermediates of -AcMetNH and -AcMetOMe via the oxidation of tryptophan (Trp) in a free aqueous solution. The reaction was examined at different pH levels. Electron transfer processes involving Trp and the sulfur-containing three-electron-bonded intermediates were investigated. The results revealed that Trp-Met pairs can form very favorable redox couples in biological systems, which is consistent with earlier reports of more efficient and rapid intramolecular charge transfers in synthetic as well as natural peptides containing methionine (Met).